ERPC functions
6.2 ERPC services and communication
CP 343-1 ERPC
Manual, 03/2010, C79000-G8976-C239-02
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● An acknowledgment
On successful completion of a logical trigger, an acknowledgment is transferred that
either confirms the correct execution of the job or contains an error message. If an error
occurs, and error identified is returned and a diagnostic message is entered in the
diagnostic buffer of the CP. The type of acknowledgment can be specified in the FB56
function block (see below).
● A time stamp
When it transfers data to the ERPC application, the CP also sends a time stamp that
contains the time at which the frame was transferred to the ERPC application.
The ERP subscriber can evaluate the time stamp, in other words, the time difference
between job and response.
Implementation of the logical trigger on the SIMATIC CPU as a function block
The logical trigger is implemented on the CPU by the function block FB56 "LOG_TRIG".
FB56 has the following tasks:
● Event-related reading of the CPU data according to the ILS Workbench configuration
● Data transfer to the CP
● Processing of the organizational data (acknowledgment identifier and status codes).
FB56 is called in the user program (OB1) at the point at which the call of the logical trigger is
required for the transfer.
You will find a detailed description of FB56 in /6/.
Other blocks
Further blocks are required for the FB56 call:
● An automatically generated instance DB
● A data block "CONF_DB"
This configuration DB contains the configuration data of the logical trigger. You make the
configuration DB available in STEP 7.
If you want to call more than one logical trigger at the same time, you will also need to
make more than one configuration DB available (see below).
The numbers of FB56 and the instance DB can be changed.
Configuring several logical triggers
You can also configure several logical triggers that are called by FB56. Each logical trigger is
configured in a separate configuration DB. If this is necessary, you will need to make several
configuration DBs available that can be called with the FB56 call in the user program. The
called trigger and the configuration DB are controlled by the block parameters "ID" and
"CONF_DB" of FB56.
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